https://www.youtube.com/watch?v=PRa6t_e7dgI
That is Dr Fauci himself on 60 minutes in early March saying that Americans should not be wearing masks. I guess he changed his mind. People want to say, "Yes he changed his mind due to new evidence." Ok what evidence? I want to see it. And it better be from just before they changed their views and not after they changed their views.
0: https://news.ycombinator.com/item?id=22777170 (claims that training is required or you're going to get rekt, read thread)
1: https://news.ycombinator.com/item?id=22776396 (while doesn't claim a no-threshold model, the threshold is a hundred viral particles)
2: https://news.ycombinator.com/item?id=22735235
3: https://news.ycombinator.com/item?id=22734656
4: https://news.ycombinator.com/item?id=22734923
5: https://twitter.com/WHOWPRO/status/1243171683067777024?s=20 (the WHO saying not to wear a mask, by the way)
6: https://news.ycombinator.com/item?id=22530340
7: https://news.ycombinator.com/item?id=22610180
8: https://news.ycombinator.com/item?id=22595955
9: https://news.ycombinator.com/item?id=22559272
If you are just looking for random people on the Internet being wrong, then yes, there are lots of examples of that!
My theory is that when people think that the guidance has radically shifted throughout the COVID-19 epidemic, it's because they are getting their information from non-authoritative sources. But like your example, sometimes the "authoritative sources" are super wrong.
Dr Fauci did eventually admit that the guidance on masks was not optimal:
> "We have to admit it, that that mixed message in the beginning, even though it was well meant to allow masks to be available for health workers, that was detrimental in getting the message across," Fauci said in an interview with Mary Louise Kelly of NPR's All Things Considered. "No doubt about it."
https://www.npr.org/sections/health-shots/2020/07/01/8862991...
What about your points 2 and 3?